A conventional fluid filled vibration isolator includes a housing having at least one flexible wall portion and a partition dividing the interior of the housing into a pair of fluid tight chambers adapted to contain a working fluid. An inertia track or passageway provides fluid communication between the two chambers, and a decoupler element is mounted in the partition and cooperates with the inertia track passageway to couple and decouple the same to control the dynamic stiffness characteristics of the isolator. The conventional decoupler may include either a diaphragm or a circular disc guided within a similarly-shaped passageway.
For a more complete discussion of the structure and operational characteristics of fluid filled vibration isolators, reference is made to an article entitled A New Generation of Engine Mounts, by Marc Bernuchon, SAE Technical Paper Series 840259, 1984, the disclosure of which is incorporated by reference herein.
In isolators having disc-type decouplers the disc can engage the wall of the passageway as the disc oscillates under certain conditions. When this occurs, friction develops, and this affects adversely the operation of the decoupler. Also, a desirable decoupler should be capable of seating tightly even when subjected to substantial pressure differentials. Furthermore, a desirable decoupler should operate noiselessly.